A preparation method and battery of TOPCon solar cell

Abstract

The present invention discloses a method for preparing a TOPCon solar cell and a cell, comprising: (1) cleaning and texturing a silicon wafer; (2) depositing a boron-containing silicon oxide layer on the front side and a tunneling silicon oxide layer and a doped polysilicon layer on the back side using a plasma-enhanced chemical vapor deposition method; (3) high-temperature annealing in a tube furnace; (4) chemical cleaning; (5) double-sided oxidation in a tube furnace; (6) depositing a first passivation film layer on the front side; (7) depositing a second passivation film layer on the back side; (8) preparing electrodes on the back side and the front side; and (9) obtaining a TOPCon solar cell after light injection treatment. The TOPCon cell prepared by the method provided by the present invention has high conversion efficiency, fewer process steps, a simpler process than traditional processes, and less equipment investment, and is suitable for commercial mass production.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar cells, and in particular relates to a preparation method of a TOPCon solar cell and a cell. Background Art

[0002] With the accelerating pace of economic globalization and the rapid development of the industrial economy, global energy shortages and environmental pollution have become major issues hindering the sustainable development of human society. The vigorous development of renewable, pollution-free energy is urgent. The inexhaustible, inexhaustible, and pollution-free nature of solar energy is gaining increasing attention from governments and individuals. With the continuous development of photovoltaic technology, solar cells, semiconductor devices that convert solar energy into electrical energy, have also seen rapid development.

[0003] In recent years, N-type solar cells have garnered widespread attention due to their low light-induced degradation, excellent stability, and bifacial power generation, contributing to their growing market share. In 2022, TOPCon mass production accelerated, and photovoltaic cell manufacturers began deploying large-scale TOPCon production lines. The key to TOPCon's mass production is its compatibility with PERC production lines, making it easier to mass-produce than other N-type cell technologies. Some organizations predict that China's TOPCon cell production capacity is expected to exceed 300GW by 2023.

[0004] However, compared with PERC technology, TOPCon technology has significantly more process steps, requiring 12-13 steps. The increase in process steps will bring difficulties to large-scale production management and control. Summary of the Invention

[0005] Purpose of the invention: The purpose of the present invention is to address the deficiencies in the prior art and to provide a novel method for preparing TOPCon solar cells and a cell thereof, which has high cell conversion efficiency, fewer process steps, a simpler process than conventional processes, and less equipment investment, making it suitable for commercial mass production.

[0006] Technical solution: The method for preparing a TOPCon solar cell according to the present invention comprises the following steps:

[0007] (1) Cleaning and texturing the silicon wafer;

[0008] (2) Plasma-enhanced chemical vapor deposition is used to deposit a boron-containing silicon oxide layer on the front side of the silicon wafer, and a tunneling silicon oxide layer and a doped polysilicon layer on the back side;

[0009] (3) Use a tube furnace to perform high-temperature annealing on the silicon wafer;

[0010] (4) Chemically clean the silicon wafer;

[0011] (5) Double-sided oxidation of silicon wafers using a tube furnace;

[0012] (6) Depositing a first passivation film layer on the front side of the silicon wafer;

[0013] (7) Depositing a second passivation film layer on the back of the silicon wafer;

[0014] (8) Prepare electrodes on the back and front of the silicon wafer;

[0015] (9) Light injection processing.

[0016] In some embodiments, in step (2), the boron-containing silicon oxide layer is deposited on the front side, and the reaction gases and flow rates required to be introduced are 1000-4000 sccm of silane, 3000-5000 sccm of nitrous oxide, 100-500 sccm of diborane, and 200-300 sccm of hydrogen.

[0017] In some embodiments, in step (2), the thickness of the front boron-containing silicon oxide layer is 60-200 nm, the thickness of the back tunneling silicon oxide layer is 1-3 nm, and the thickness of the doped polysilicon layer is 50-250 nm.

[0018] In some embodiments, in step (2), the doping elements in the doped polysilicon layer are phosphorus and carbon.

[0019] In some embodiments, in step (2), the deposition of the doped polysilicon layer requires the introduction of reaction gases and flow rates of silane 1500-5000 sccm, phosphine 300-2500 sccm, methane 50-300 sccm, and nitrogen 4000-7000 sccm, respectively.

[0020] In some embodiments, in step (3), the gases and flow rates used for the high temperature annealing are respectively 1000-5000 sccm for oxygen and 500-8000 sccm for nitrogen, the temperature is 900-1080° C., and the time is 90-135 min.

[0021] In some embodiments, in step (5), the double-sided oxidation is to simultaneously grow a silicon oxide layer on both the front and back sides, with the temperature controlled at 550-750° C. and a thickness of 3-6 nm.

[0022] In some embodiments, in step (6), the first passivation film layer includes an aluminum oxide layer and a composite dielectric layer deposited sequentially from the inside to the outside, and the composite dielectric layer includes one or more of a silicon nitride layer, a silicon oxynitride layer, and a silicon oxide layer; the thickness of the aluminum oxide layer is 6-20 nm, and the thickness of the composite dielectric layer is 55-90 nm.

[0023] In some embodiments, in step (7), the second passivation film layer includes one or more of a silicon nitride layer, a silicon oxynitride layer, and a silicon oxide layer, and the total thickness thereof is 60-95 nm.

[0024] On the other hand, the present invention also discloses a TOPCon solar cell, which is prepared by the preparation method.

[0025] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0026] Through the plasma-enhanced chemical vapor deposition method, a solid boron source is continuously deposited on the front side, and the silicon oxide layer and the doped polysilicon layer are tunneled through the back side. Finally, a one-step annealing method is used to complete the production of the front boron emitter and the crystallization of the doped polysilicon on the back side. This can effectively reduce the process steps of the TOPCon battery, reduce the number of equipment, and improve production capacity.

[0027] In addition, the boron emitter produced using plasma-enhanced chemical vapor deposition has the advantages of no boron-rich layer, little damage to the velvet pyramid, no wrap-around plating, and good uniformity, making it fully feasible for the industrial preparation of high-efficiency TOPCon batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The figure is a schematic flow chart of a method for preparing a TOPCon solar cell according to an embodiment of the present invention. Implementation Method

[0029] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0030] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "inside", "outside", etc., indicating the orientation or position relationship are the orientation or position relationship shown, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0031] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0032] The present invention will be further described in detail below through specific implementation examples in conjunction with the accompanying drawings. Example

[0033] like Figure 1 As shown, a method for preparing a TOPCon solar cell and a battery, the process includes:

[0034] S01: Cleaning and texturing of N-type silicon wafers;

[0035] S02: Using plasma enhanced chemical vapor deposition, a boron-containing silicon oxide layer is deposited on the front side, and a tunneling silicon oxide layer and a doped polysilicon layer are deposited on the back side;

[0036] S03: High temperature annealing using a tube furnace;

[0037] S04: Chemical cleaning;

[0038] S05: Use a tube furnace to grow silicon oxide layers on both the front and back sides;

[0039] S06: depositing a first passivation film layer on the front side;

[0040] The first film layer includes an aluminum oxide layer and a composite dielectric layer deposited in sequence from the inside to the outside. The composite dielectric layer includes one or more of a silicon nitride layer, a silicon oxynitride layer and a silicon oxide layer. The silicon nitride layer, the silicon oxynitride layer and the silicon oxide layer are independent layers. The three layers are deposited in no particular order and have a variety of arrangements. Among them, the aluminum oxide layer, the silicon nitride layer, the silicon oxynitride layer and the silicon oxide layer are single layers or multiple layers. The multilayer means: the aluminum oxide layer can be deposited in multiple layers, the silicon nitride layer can be deposited in multiple layers, the silicon oxynitride layer can be deposited in multiple layers, and the silicon oxide layer can be deposited in multiple layers.

[0041] S07: depositing a second passivation film layer on the back side;

[0042] The second passivation film layer includes one or more of a silicon nitride layer, a silicon oxynitride layer and a silicon oxide layer. The silicon nitride layer, the silicon oxynitride layer and the silicon oxide layer are independent layers. The three layers are deposited in no particular order and have a variety of arrangements. Among them, the silicon nitride layer, the silicon oxynitride layer and the silicon oxide layer are single layers or multiple layers.

[0043] S08: Prepare electrodes on the back and front sides respectively;

[0044] S09: light injection processing; Example

[0045] A method for preparing a TOPCon solar cell comprises the following steps:

[0046] (1) Select an N-type silicon wafer with a resistivity of 1.0 Ω.cm and texturize the wafer using an alkaline solution and a texturizing additive;

[0047] (2) Place the silicon wafer in a plasma-enhanced chemical vapor deposition (PECVD) apparatus and first deposit a solid boron-containing silicon oxide layer, introducing 3000 sccm of silane, 4200 sccm of nitrous oxide, 230 sccm of diborane, and 290 sccm of hydrogen as the reaction gases, to a thickness of 160 nm. Then, a tunneling silicon oxide layer and a doped polysilicon layer are deposited on the back side, introducing 1500 sccm of oxygen, 2800 sccm of silane, 1300 sccm of phosphine, 120 sccm of methane, and 5500 sccm of nitrogen as the reaction gases, to a tunneling silicon oxide layer thickness of 1.7 nm and a doped polysilicon layer thickness of 120 nm.

[0048] (3) Annealing in a tube furnace at 980°C for 110 min, with oxygen at 3000 sccm and nitrogen at 5000 sccm.

[0049] (4) Chemical cleaning to remove the oxide layer on the front and back sides and the PN junction at the edge after annealing;

[0050] (5) Continue to use the tube furnace to grow the silicon oxide layer on the front and back sides, the process temperature is 650℃, and the silicon oxide thickness is 3nm;

[0051] (6) Depositing the first film layer on the front side, the first film layer includes an aluminum oxide layer and a composite dielectric layer. Specifically, first depositing an aluminum oxide layer with a thickness of 16 nm, and then depositing the composite dielectric layer of a silicon nitride layer, a silicon oxynitride layer, and a silicon oxide layer in sequence, wherein the thickness of the silicon nitride layer is 35 nm, the thickness of the silicon oxynitride layer is 30 nm, and the thickness of the silicon oxide layer is 10 nm;

[0052] (7) depositing a second film layer on the back side, the second film layer comprising a silicon nitride layer, a silicon oxynitride layer, and a silicon oxide layer, wherein the thickness of the silicon nitride layer is 30 nm, the thickness of the silicon oxynitride layer is 25 nm, and the thickness of the silicon oxide layer is 25 nm;

[0053] (8) Printing silver paste on the back and silver-aluminum paste on the front by screen printing, and completing the metal electrode after sintering;

[0054] (9) After further processing by light injection (light intensity 13000 W / m2), the preparation of the TOPCon solar cell is completed.

[0055] Comparative Example

[0056] The traditional TOPCon battery manufacturing process includes: texturing, boron diffusion in a tubular diffusion furnace, alkaline polishing, back-side deposition of tunneling oxide layer and doped polysilicon, high-temperature annealing, chemical cleaning, front-side deposition of the first film layer, back-side deposition of the second film layer, and preparation of front and back metal electrodes.

[0057] Comparison of the results of the embodiment and the comparative example:

[0058] Table 1 Characterization results of examples and comparative examples

[0059] Grouping iVoc(mV) J0(fA / cm2) Example 2 745 3.0 Comparative Example 743 3.1

[0060] Table 2 Electrical performance results of examples and comparative examples

[0061] Grouping Uoc(V) Isc(A) FF(%) Efficiency(%) Example 2 0.7139 13.341 83.74 24.16 Comparative Example 0.7128 13.343 83.81 24.14

[0062] By comparing the data in Table 1, the passivation characterization results of the embodiment are slightly improved compared with the comparative example; by comparing the data in Table 2, the electrical performance of the embodiment is improved by 0.02% compared with the comparative example.

[0063] The above data show that the preparation method and battery of a TOPCon solar cell of the present invention have advantages in test results compared with the current traditional preparation methods, and it can effectively reduce the production process steps and has application prospects for mass production.

[0064] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with this profession can make some changes or modifications to equivalent embodiments of the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a TOPCon solar cell, characterized in that: The steps include: (1) Cleaning and texturing the silicon wafer; (2) Plasma-enhanced chemical vapor deposition is used to deposit a boron-containing silicon oxide layer on the front side of the silicon wafer, and a tunneling silicon oxide layer and a doped polysilicon layer on the back side; The boron-containing silicon oxide layer is deposited on the front side, and the reaction gases and flow rates required to be introduced are silane 1000-4000 sccm, nitrous oxide 3000-5000 sccm, diborane 100-500 sccm, and hydrogen 200-300 sccm; The doping elements in the doped polysilicon layer are phosphorus and carbon. The reaction gases and flow rates required for depositing the doped polysilicon layer are 1500-5000 sccm of silane, 300-2500 sccm of phosphine, 50-300 sccm of methane, and 4000-7000 sccm of nitrogen. (3) Using a tube furnace to perform high-temperature annealing on the silicon wafer, the gases and flow rates used for the high-temperature annealing are respectively 1000-5000 sccm of oxygen and 500-8000 sccm of nitrogen, the temperature is 900-1080°C, and the time is 90-135 minutes; (4) Chemically clean the silicon wafer; (5) Double-sided oxidation of silicon wafers using a tube furnace; (6) Depositing a first passivation film layer on the front side of the silicon wafer; (7) Depositing a second passivation film layer on the back of the silicon wafer; (8) Prepare electrodes on the back and front of the silicon wafer; (9) Light injection processing.

2. The method for preparing a TOPCon solar cell according to claim 1, wherein: In step (2), the thickness of the front boron-containing silicon oxide layer is 60-200 nm, the thickness of the back tunneling silicon oxide layer is 1-3 nm, and the thickness of the doped polysilicon layer is 50-250 nm.

3. The method for preparing a TOPCon solar cell according to claim 1, wherein: In step (5), the double-sided oxidation is to grow silicon oxide layers on both the front and back surfaces simultaneously, with the temperature controlled at 550-750°C and a thickness of 3-6nm.

4. The method for preparing a TOPCon solar cell according to claim 1, wherein: In step (6), the first passivation film layer includes an aluminum oxide layer and a composite dielectric layer deposited sequentially from the inside to the outside, and the composite dielectric layer includes one or more of a silicon nitride layer, a silicon oxynitride layer, and a silicon oxide layer; the thickness of the aluminum oxide layer is 6-20 nm, and the thickness of the composite dielectric layer is 55-90 nm.

5. The method for preparing a TOPCon solar cell according to claim 1, wherein: In step (7), the second passivation film layer includes one or more of a silicon nitride layer, a silicon oxynitride layer and a silicon oxide layer, and the total thickness thereof is 60-95 nm.

6. A TOPCon solar cell, characterized in that: The battery is prepared by the preparation method according to any one of claims 1 to 5.

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